
(function (doc, win) {  
    var docEl = doc.documentElement,  
    resizeEvt = 'orientationchange' in window ? 'orientationchange' : 'resize',  
    recalc = function () {  
    var clientWidth = docEl.clientWidth;  
    if (!clientWidth) return;  
    docEl.style.fontSize = 20 * (clientWidth / 320) + 'px';  
    };  
  
    if (!doc.addEventListener) return;  
    win.addEventListener(resizeEvt, recalc, false);  
    doc.addEventListener('DOMContentLoaded', recalc, false);  
})(document, window);  

